The present invention is related to hang tabs and more particularly to hang tabs provided with a pressure-sensitive coating provided on at least one of its two surfaces.
There is known U.S. Pat. No. 5,542,634 comprising an adhesive hang tab provided with channels in the adhesive zone to limit and arrest peel propagation.
There are also known U.S. Pat. Nos. 5,020,761; 4,890,809 and 4,863,128 describing various forms of adhesive hang tabs.
There are many models of hang tabs that are used to display products on peg hook at retail, however in these and other conventional tab designs, the adhesive zone is generally of rectangular configuration. The reason for such configuration relates to simplicity of design and ease of manufacture.
Typically, the conventional production of hang tabs uses a rotary die-cutting process, wherein a lamination consisting of a continuous strip of releasable paper liner, adhesive and flexible plastic are passed under a rotary die-cutting blade which will cut out the desired shape of the tab.
In the effort to economize on material between pieces, and to minimize tooling costs, it is often desirable to have adjacent pieces to share the same common cutting edges. As a result, while no material in the adhesive zones need to be discarded, the final pieces have sharp corners (see FIGS. 1 and 2) which is undesirable in use.
Using this conventional method, if rounded corners are desired, it is necessary to separate or space the layout of pieces on the tool so that corners of the final piece can be rounded (see FIG. 3). However, it then becomes necessary to discard the material between adjacent pieces, which produces undesirable and costly waste material.
Whether conventional corners are rounded or squared, the resulting adhesive zone of the tab is always substantially rectangular.
The analysis made by the inventor of the present invention had proven that once an article is suspended by the hang tab, the shear forces in the adhesive zone are not distributed uniformly across the adhesive zone. Referring to FIG. 4 there is illustrated a two dimensional plane stress analysis conducted using Ansys Software version 5.5.1 using finite element analysis of 10,000 nodes of a conventionally shaped hang tab made of a semi-rigid material with modulus of elasticity of 290,000 psi with Poisson ration of 0.4 and tab thickness of 0.014 inches.
For the purpose of this simulation, a one unit point load was applied upward to the top of the aperture, while the adhesive zone supported a flat body with a weight of one unit. As diagram of the shear load of FIG. 4 indicates, the stress distribution across the adhesive zone of the tab is such that the shear load stresses are concentrated in the laterally remote portions of the adhesive zone, while the lower mid-section of the adhesive zone experiences only minor shear stresses. This discovery indicates that the lower central portion of the adhesive zone of the tab contributes proportionably less by area to support the vertical load compared to laterally extreme portions of the adhesive zone. The analysis shows that the lower central portion comprising 33% of the adhesive zone area contributes less than 1% to support the vertical load.
The present invention is based on this discovery and provides the improved configuration of the adhesive zone resulting in more material efficient product by using optimized geometry of the hang tab.
Another beneficial feature of the present invention is that adjacent tabs can be configured to share a common edge in combination with a possibility to make all outer corners rounded without having to generate waste material. The only sharp blended edge is interior of the adhesive zone of the piece and this sharp point is not exposed during use.
According to the present invention there is provided an adhesive hang tab for suspension of an object to a support, comprising a main body having two opposite surfaces, said main body is divided into a non-coated upper portion provided with an aperture adapted for secure suspension of said object onto said support and an adhesive lower portion provided with a pressure-sensitive coating; said adhesive portion is further provided with two legs extending laterally downwardly from said adhesive portion, said legs being also provided with the pressure-sensitive coating; wherein said legs are forming a channel spaced between said legs.
In one embodiment said channel having a substantially rectangular configuration. In the other embodiment all corners of said hang tab and inner corners of said channel are being rounded.
The present invention may further be provided with at least two slits extending from said central aperture into said lower adhesive portions, said slits are provided to resist peeling force during the use.
According to the present invention there is also provided a method of making an adhesive hang tabs, said method comprising:
applying a liner strip and an adhesive pressure-sensitive coating to designated areas of a tab substrate to form a composite tab substrate; and
die-cutting a plurality of hang tabs from said composite tab substrate in a such manner that said tabs are arranged on said substrate in at least two opposing interlocking rows, wherein legs of hang tabs of one row are facing legs of hang tabs of the opposite row, and wherein adjacent legs of two hang tabs of said one row are accommodated within a channel formed between legs of one hang tab of the opposing row.
In one embodiment hang tabs of each of said opposing interlocking rows are placed side by side without any gaps left between each adjacent tab and the legs of said one row is interlocked within channels between legs of said another row without any gap left within said channels.